Jan 24-26 Weekend Snow and Sleetfest Model Thread Part Tres

[high risk]

6 minutes ago, stormtracker said:

maybe @high risk can explain.  Maybe lends to NAM being too dry.   Weenie hope

        It's pretty clear that the NAM is slow with the leading edge of the precip.    It definitely has a bias of being too slow to advance precipitation into very dry air.     The 18Z cycle doesn't bring snow into DC until 6Z, and I doubt it will take that long.   It's probably good reason to ignore its QPF for the front end thump and go with wetter models.    That said, none of that means that it must be off with the timing of the transition to sleet.    It might very well be too fast with that, but I wouldn't base that off of not getting snow to the ground quickly enough at the leading edge.

[high risk]

4 minutes ago, DDweatherman said:

that actually made me laugh out loud. Serious question for a sec, why did the FV3 GFS replacement never game big time? 
 

on this storm, it has been consistently colder and snowier for most than the other suites, but not all that different than the OP GFS. Does it have a published cold bias that just can’t be corrected? 

     With apologies, what do you mean by the "FV3 GFS replacement"?   

[Snowciopathic Snow Bro]

ZR reduction/deletion, ftw!  Trees, you can stop exploding or falling down now.

[jayyy]

Weenie alert, but it would be huge if we could get the snow in here this evening instead of after midnight. The delay in this storm definitely hurt us getting to those bigger totals.

Not sure the exact time of day matters. It’s all about when the 850 low and primary start encroaching to our west. If it starts 3 hours earlier and flips over 3 hours earlier, doesnt really do us any good


.

[Solution Man]

Thickening clouds 19F/-9F, pressure falling

[mitchnick]

2 minutes ago, high risk said:

        It's pretty clear that the NAM is slow with the leading edge of the precip.    It definitely has a bias of being too slow to advance precipitation into very dry air.     The 18Z cycle doesn't bring snow into DC until 6Z, and I doubt it will take that long.   It's probably good reason to ignore its QPF for the front end thump and go with wetter models.    That said, none of that means that it must be off with the timing of the transition to sleet.    It might very well be too fast with that, but I wouldn't base that off of not getting snow to the ground quickly enough at the leading edge.

Well if it's light with precip and precip does provide some dynamic cooling, that might rectify the desparity between it and the models that changeover 1 or 2 hours later.

But what do I know, I'm just trying to get a head start in life post retirement. 

[notvirga!]

Snow making its way up. Snowing north of Blacksburg VA already. Will be snowing around Natural bridge very soon 

[BTRWx's Thanks Giving]

19Z hrrr is juicy, but kind of out of range. I'll just share a link.

https://www.tropicaltidbits.com/analysis/models/?model=hrrr&region=neus&pkg=asnowd&runtime=2026012419&fh=18

 

[EastCoast NPZ]

1 minute ago, Snowciopathic Snow Bro said:

ZR reduction/deletion, ftw!  Trees, you can stop exploding or falling down now.

Lurker and Tracker will not welcome that news 

[Terpeast]

Just now, Snowciopathic Snow Bro said:

ZR reduction/deletion, ftw!  Trees, you can stop exploding or falling down now.

That is very very good news… not from a “potentially snowier” weenie perspective, but in terms of perhaps less impacts/power outages/accidents. 

[osfan24]

1 minute ago, jayyy said:

Not sure the exact time of day matters. It’s all about when the 850 low and primary start encroaching to our west. If it starts 3 hours earlier and flips over 3 hours earlier, doesnt really do us any good


.

My thought was we just get extra snow breaking out ahead and the flip time doesn’t change.

[DDweatherman]

3 minutes ago, high risk said:

     With apologies, what do you mean by the "FV3 GFS replacement"?   

I thought the fv3 was the next gen gfs? And I had heard here it wasn’t going to make it to the big game for a while still if it did

[osfan24]

1 minute ago, BTRWx's Thanks Giving said:

19Z hrrr is juicy, but kind of out of range. I'll just share a link.

https://www.tropicaltidbits.com/analysis/models/?model=hrrr&region=neus&pkg=asnowd&runtime=2026012419&fh=18

 

Ehh, showed 8 inches for Central MD a couple runs ago so that looks worse flip is delayed a few hours at least.

[bncho]

What does the precip arriving earlier implicate?

[high risk]

Just now, DDweatherman said:

I thought the fv3 was the next gen gfs? And I had heard here it wasn’t going to make it to the big game for a while still if it did

        The GFS does use the FV3 core now.     That has been the case since 2019.

[BTRWx's Thanks Giving]

Just now, osfan24 said:

Ehh, showed 8 inches for Central MD a couple runs ago so that looks worse flip is delayed a few hours at least.

Still snowing after 18h.

[BristowWx]

2 minutes ago, Solution Man said:

Thickening clouds 19F/-9F, pressure falling

20/-9. That sleet will be extra ping-y.  Just hoping for SN/IP mix.  Just makes it nicer for viewing. 

[Snowciopathic Snow Bro]

1 minute ago, Terpeast said:

That is very very good news… not from a “potentially snowier” weenie perspective, but in terms of perhaps less impacts/power outages/accidents. 

Aye.  One element that hasn't been mentioned much since we're so focused on QPF/storm track right now is the wind picking up during the day Monday once this mess clears the area.  Definitely don't want thick treecycles exposed to 30 mph gusts.

[WEATHER53]

45 minutes ago, baltosquid said:

Yeah big signal for a cave on the super aggressive mixing line advancement... I hope. Still have until 00z to get a bad run in before game time!

I still think even though others dissented that models are not programmed to handle at 30.70 to 30.50 baro freshly placed over top of us 

[Solution Man]

 

 

Reflectivity 

 

 

[MN Transplant]

9 minutes ago, high risk said:

     With apologies, what do you mean by the "FV3 GFS replacement"?   

 

14 minutes ago, DDweatherman said:

that actually made me laugh out loud. Serious question for a sec, why did the FV3 GFS replacement never game big time? 
 

on this storm, it has been consistently colder and snowier for most than the other suites, but not all that different than the OP GFS. Does it have a published cold bias that just can’t be corrected? 

I have just enough knowledge of this to be dangerous, but high risk can correct me.  Models have a dynamical core and various physics packages.  About a decade ago NOAA/NWS decided to try to align all of the operational models with a single dynamical core.  The FV3 was chosen but there have been some problems with it when it is run at finer convection-allowing resolution.  So, the alternative was MPAS (model for prediction across scales) from NCAR.  I know that NSSL has been testing out MPAS a lot and that one may end up being the dynamical core.  One of the problems with MPAS, though, is that it is computing-hungry compared to FV3.  So, NOAA is weighing pros and cons.

[stormy]

The EURO continues to harp heavy ZR amounts. For Augusta .86".  This is not going to happen.

IMO, the 925 temp profiles are too cold.   Most of that Euro predicted zr will be sleet.

[BristowWx]

My son is reporting SN at Radford, VA.  He’s usually drunk but good at obs. They are lighting pallets on fire now in. Celebration .  He has not seen the 3k NAM.  

[MN Transplant]

The Canadians finally thawed.  12z GDPS seems healthy precip wise.  Guessing a 14Z changeover after maybe 0.7"?

12z RDPS either had something wrong with the run or with the transmission.  Not on Pivotal, but it is partially on College of Dupage.  Same 14z changeover timing.  No precip amounts available, but looks healthy from the precip rate/type maps.

 

[WxUSAF]

36 minutes ago, high risk said:

The blanket "the NAM sucks" stuff is wild to me when the strength of the NAM Nest is nailing thermal profiles inside of Day 2.   Maybe it's going to be too fast with the changeover, but complete dismissing of it makes no sense.

Definitely not dismissing it for us. I’m mentally assuming a changeover somewhere between the times the NAM and euro suggest. Maybe 15-16z for us?

[grhqofb5]

5 minutes ago, stormy said:

The EURO continues to harp heavy ZR amounts. For Augusta .86".  This is not going to happen.

IMO, the 925 temp profiles are too cold.   Most of that Euro predicted zr will be sleet.

I guess the Masters is going to have to truck in a bunch of sod come April.

[high risk]

7 minutes ago, MN Transplant said:

 

I have just enough knowledge of this to be dangerous, but high risk can correct me.  Models have a dynamical core and various physics packages.  About a decade ago NOAA/NWS decided to try to align all of the operational models with a single dynamical core.  The FV3 was chosen but there have been some problems with it when it is run at finer convection-allowing resolution.  So, the alternative was MPAS (model for prediction across scales) from NCAR.  I know that NSSL has been testing out MPAS a lot and that one may end up being the dynamical core.  One of the problems with MPAS, though, is that it is computing-hungry compared to FV3.  So, NOAA is weighing pros and cons.

              You are spot on.   MPAS is going to replace FV3 in RRFS Version 2, and it will probably be used across the board eventually in the NWS models.

[Weather Will]

WB 18Z ICON snowfall is an improvement.

[high risk]

1 minute ago, WxUSAF said:

Definitely not dismissing it for us. I’m mentally assuming a changeover somewhere between the times the NAM and euro suggest. Maybe 15-16z for us?

      I would love if it takes that long, but I'm mentally prepared for 13-14z.  

[WEATHER53]

25 minutes ago, EHoffman said:

I maintain we always start ahead of schedule on these WAA events 

And almost always sooner is better than later for DC. Don’t know why but it’s observationally correct